Missing FFI type safety checks

I tried this code: https://github.com/rust-lang/rust/blob/aa3ca1994904f2e056679fce1f185db8c7ed2703/src/test/ui/issue-14309.rs

https://godbolt.org/z/GjGG3jTh4

struct A {
    x: i32
}

#[repr(C, packed)]
struct B {
    x: i32,
    y: A
}

#[repr(C)]
struct C {
    x: i32
}

type A2 = A;
type B2 = B;
type C2 = C;

#[repr(C)]
struct D {
    x: C,
    y: A
}

extern "C" {
    fn foo(x: A); //~ ERROR type `A` which is not FFI-safe
    fn bar(x: B); //~ ERROR type `A`
    fn baz(x: C);
    fn qux(x: A2); //~ ERROR type `A`
    fn quux(x: B2); //~ ERROR type `A`
    fn corge(x: C2);
    fn fred(x: D); //~ ERROR type `A`
}

fn main() { }

I expected to see this happen: errors that type 'A' is not FFI-safe

Instead, this happened: compile-without error

Meta

• What version of Rust GCC were you using, git sha if possible. be27571c110d99fe55324a9c2b6622787b08fb52

Start by reproducing the example from src/test/ui/issue-14309.rs with the reported Rust GCC revision, using the linked Godbolt case if helpful. Trace the compiler's FFI-safety diagnostics for A, packed B, aliases A2/B2, and nested D; done means the expected errors are emitted while C and C2 remain accepted.